Vast Space LLC, the aerospace startup founded by former crypto tycoon Jed McCaleb, has hired SpaceX to launch two private astronaut missions to the International Space Station, part of its plans to commercialize Earth’s orbit.  The deal, announced on Thursday, is contingent on Vast winning a bid to participate in a NASA program that promotes sending private astronauts to the orbiting research lab. Since 2019, NASA has allowed companies to send civilian crews to the ISS, helping these firms better understand the costs and challenges of operating space stations.

Vast is among a number of companies competing to usher in a future when humans live and work on commercial space stations.

If picked, Vast would utilize SpaceX’s workhorse Falcon 9 rocket and Dragon capsule to launch the fifth and sixth of these NASA-enabled missions, Vast said.

So far, Vast rival Axiom Space Inc. has launched three private astronaut missions to the ISS on SpaceX Dragon flights, with plans to fly a fourth one in 2025.

Read More: SpaceX Launches First Private Astronaut Mission to Space Station

If selected by NASA, it would mark a significant partnership with the space agency as Vast competes against the likes of Axiom and Jeff Bezos-backed Blue Origin LLC to develop a successor to the International Space Station — scheduled to be retired in 2030.

In October, Vast revealed plans for an orbiting hub called Haven-2, a specialized lab in low-Earth orbit which will contend with other designs as NASA picks finalists for ISS successors in 2026.

Thursday’s announcement is the latest in a series of close partnerships that Vast holds with Elon Musk’s SpaceX, which will also be launching Vast’s precursor commercial space station, called Haven-1, no earlier than August 2025.

SpaceX and Vast also plan to launch a crew to visit Haven-1 once the vehicle is in orbit. Plus, Haven-1 will also feature internet connection enabled by Starlink, SpaceX’s satellite internet service.